1. Field of the Invention
The present invention relates to an air conditioner with a dual function of cooling and heating operations, and more particularly to a heating control apparatus of an air conditioner and method thereof to control an indoor fan according to temperature of a heat-exchanger at an initial heating stage to prohibit cool air from being discharged indoors.
2. Description of the Prior Art
Generally, an air conditioner includes a heating apparatus for supplying warm air by heating cold room air and a cooling apparatus for supplying cool air by cooling warm room air. Besides, a heating and cooling apparatus is also included for a dual function of heating and cooling operations and an air purifying which cleans polluted room air.
FIGS. 1 and 2 illustrate an indoor unit of the heating and cooling apparatus (generally, referred as an air conditioner) among conventional air conditioners. As shown in FIG. 1, an suction grille member(5) is provided at the lower front surface of an indoor unit main body (hereinafter referred to as a main body) with a plurality of suction inlets(3) to suck room air and with a plurality of discharge outlets(7) at the upper front surface of the main body to discharge the heat-exchanged air, i.e., the heated or cooled air, that is sucked through the suction inlets(3).
Furthermore, the discharge outlets(7) comprises vertical vanes(9) and horizontal vanes(11) for controlling the vertical and horizontal directions of the air discharged indoors therethrough, a covering member(13) attached for forming an external appearance thereof and for protecting the interior parts therein, and a controlling part(15) disposed at the lower portion of the cover member(13) for controlling overall operational modes (automatic, cooling, dehumidifying, blowing, heating, etc.) of the air conditioner, a start or stop operation thereof and the amount and direction of the air discharged through the discharge outlets(7).
As shown in FIG. 2, there are a filtering member(17) disposed at the inner side of the suction grille member(5) for filtering dust and foreign objects floating with the room air sucked through the suction inlets(3) and a heat-exchanger(19) behind the filtering member(17) for heat-exchanging into heated air or cooled air through evaporative latent heat of a coolant.
In addition, the heat-exchanger(19) is disposed thereon with a blower fan(23) (hereinafter referred as indoor fan) which rotates according to operation of an indoor fan motor in order to suck the room air through the suction inlets(3) and, at the same time, to discharge through the discharge outlets(7) the air heat-exchanged at the heat-exchanger(19). The indoor fan(23) is also provided with a duct member(25) outside thereof for covering the indoor fan(23) and for guiding the stream of the air sucked through the suction inlets(3) and discharged through the discharge outlets(7).
In an inverter air conditioner with a dual function of heating and cooling operations, the coolant is circulated in the following sequence: compressor(39)--four way valve(31)--indoor heat-exchanger(19)--expansion valve(33)--heating expansion valve(34)--outdoor heat-exchanger(35)--four way valve(31)--compressor(39), as shown in a dotted line in FIG. 3 when the four way valve(321) is turned on for the heating operation.
On the other hand, when the four way valve(3 1) is turned off for the cooling operation, the coolant is circulated in the following sequence: compressor(39)--four way valve(31)--outdoor heat-exchanger(35)--one way valve(36)--expansion valve(33)--indoor heat-exchanger(19)--four way valve(31)--compressor(39) as shown in a straight line in FIG. 3. At this time, the four way valve(31) controls the circulation route of the coolant in the straight line or in the dotted line respectively when the four way valve(31) is turned off or on.
In the inverter air conditioner with a dual function of cooling and heating operations, an user turns on a start/stop key (hereinafter referred to as an operation key) with a remotely controlled unit or with the operating part(15) and selects a desired operation mode (for instance, heating). When the set temperature (Ts) is higher than the room temperature (Tr), an operation frequency of the compressor(39) is determined by the temperature difference between Ts and Tr to drive the compressor(39).
When the compressor(39) is driven, the coolant is circulated in the following sequence, as shown in the dotted line in FIG. 3: compressor(39)--four way valve(31)--indoor heat-exchanger(19)--expansion valve(33)--heating expansion valve(34)--outdoor heat-exchanger(35)--four way valve(31)--compressor (39), to thereby heat the indoor heat-exchanger(19). Operation of the indoor fan(23) is controlled according to the temperature of the indoor heat-exchanger(19).
If the temperature of the indoor heat-exchanger(19) is lower than the predetermined temperature (about 27.degree. C.), the indoor fan(23) is stopped to prevent cool air from being discharged indoors at the initial heating stage. If the temperature of the indoor heat-exchanger(19) is higher than the predetermined temperature (about 27.degree. C.), the indoor fan(23) is operated.
If the indoor fan(23) is operated, the dust and foreign objects floating in the room air are sucked through the suction inlets(3) into the main body(l) to be removed by the filtering member(17). The purified room air is heat-exchanged into warn air by way of evaporative latent heat of the coolant at the indoor heat-exchanger(19).
The warm air heat-exchanged at the indoor heat exchanger(19) is guided upwards and discharged indoors through the discharge outlets(7). The warm air discharged through the discharge outlets(7) carries out the heating operation at air directions according to the angles of the vertical vanes(9) and the horizontal vanes(11).
When the temperature of the indoor heat-exchanger(19) lowers under the predetermined temperature by the room temperature(Tr), the indoor fan(23) is to be turned off. If this phenomenon is repeated, the heating operation can not be properly carried out. While the compressor(39) is in operation, the warm coolant tends to be continuously supplied into the indoor heat-exchanger(19). Even though the temperature of the indoor heat-exchanger(19) lowers under the predetermined temperature (about 24.degree. C.), the compressor(39) can be in continuous operation carrying out the heating operation without turning off the indoor fan(23).
There is a problem in the conventional heating control apparatus in that cool air can be continuously discharged without properly responding to the change of the room temperature when the compressor(39) is in continuous operation driving the indoor fan(23) even if the temperature of the indoor heat-exchanger(19) lowers under the predetermined temperature (about 24.degree. C.).